Here we'll show you how to depart from a class Delta airport and request VFR flight following while on the ground before departure. This way you will already have your squawk code assigned and a departure frequency assigned to you before you take off from the class D airport. This is very similar to how you would depart a class charlie airport, receiving a squawk code and departure frequency before changing from ground to the tower frequency. https://youtu.be/4iquR2MZg9A